Great white sharks are terrified of orcas, research shows

Rodiano Bonacci
Aprile 20, 2019

From 2006 to 2013 there was a number of 165 great whites the scientists aimed, attracting them with seal decoys created out of carpets to the boats, and then attaching to their bodies beacons that sent data to sensors all over their area.

The surprising beneficiary of the sharks' swift exit were elephant seals, who were killed much less frequently in the seasons when the whales appeared.

Since the premiere of Jaws in movie theaters, the great white shark has been one of the most feared animals on the planet. The team notes that the white sharks are enormous with some over 18-feet long. Orcas have toppled the great white shark off their "apex predator" throne. "By supplementing the Aquarium's new shark tagging data with Point Blue's long-term monitoring of wildlife at the Farallon Islands National Wildlife Refuge, we were able to conclusively show how white sharks clear out of the area when the orcas show up".

Researchers from the Monterey Bay Aquarium and partner institutions have found that great white sharks may not be the most formidable predators in the ocean. Researchers suspect it could be because the sharks are prey for the orcas, or possibly because they are bullied over food and ultimately forced out.

In addition, orcas have been observed preying on great white sharks around the world, including near the Farallon Islands.

In the few instances where the predators overlapped, the sharks would swim away within minutes.

According to the scientists, each predator acted differently when they were in the same vicinity: Whenever the orcas showed up to feed on elephant seals, great white sharks started swimming offshore or gathering together at other seal colonies along the coastline.

The scientists found that this vacating of hunting grounds by the sharks occurs even if the orcas are only passing through the area.

Previously, orcas have been known to kill sharks and eat their livers.

"We don't typically think about how fear and risk aversion might play a role in shaping where large predators hunt and how that influences ocean ecosystems", added Salvador Jorgensen, the study's lead author.

In all the cases the scientists examined, the white sharks fled the sanctuary when orcas arrived and didn't return until the following season. White sharks gather in the area the researchers were investigating each fall between September and December to hunt for young elephant seals. This was true even when the killer whales were present for less than an hour.

"Occasional consumption of the highly-caloric liver of white sharks may confer ancillary energetic benefits to the killer whale", the study says.

Concluding, it says: "Future efforts should aim to measure the impact and ecological implications of these risk effects on white shark fitness and elephant seal population dynamics".

Altre relazioniGrafFiotech

Discuti questo articolo

Segui i nostri GIORNALE